Multispectrum analysis of self- and N-2-broadening, shifting and line mixing coefficients in the nu(6) band of (CH3D)-C-12

A multispectrum nonlinear least-squares fitting technique has been applied to determine accurate zero-pressure line center positions, Lorentz self- an d N-2-broadening coefficients and self- and N-2-induced pressure shift coef ficients of transitions in the nu (6) (E) perpendicular band of (CH3D)-C-12 between 1035 and 1270 cm(-1). Seventeen high-resolution (0.002-0.006 cm(-1 )) room temperature absorption spectra recorded with two Fourier transform spectrometers (FTS) were analyzed together. Self-broadening coefficients fo r over 700 transitions and self-shift coefficients for more than 600 transi tions were determined. Measurements of nitrogen-broadening coefficients for more than 480 transitions and nitrogen pressure induced shift coefficients for nearly 430 transitions were also made. The measurements include transi tions with rotational quantum numbers as high as J " = 18 and K " = 15 and several forbidden transitions. The measurements were made in all six sub-ba nds (P-P, (P)Q, R-P, P-R, (R)Q and R-R). The measured self-broadening coeff icients vary from 0.025-0.096 cm(-1) atm(-1) at 296 K and the N2-broadening coefficients from 0.02 to 0.08 cm(-1) atm(-1) at 296 K. Self-induced-shift coefficients range from -0.014 to +0.004 cm(-1) atm(-1) while the nitrogen -induced-shift coefficients vary from -0.013 to +0.008 cm(-1) atm(-1). Very few of the measured pressure-shift coefficients were positive, and the pos itive shift coefficients were mostly associated with the J " = K " transiti ons in the (P)Q sub-bands. The off-diagonal relaxation matrix element coeff icients of a number of transitions with K " = 3 doublets for both self- and N-2-broadening were also obtained. The results obtained with the two diffe rent broadening gases are compared and discussed. Comparisons with previous values from the literature are also made. (C) 2001 Elsevier Science Ltd. A ll rights reserved.